As used in —

((a)) The term “mortgage” means (A) a first mortgage on real estate, in fee simple, (B) a first mortgage on a leasehold on real estate (i) under a lease for not less than ninety-nine years which is renewable, or (ii) under a lease having a period of not less than ten years to run beyond the maturity date of the mortgage, or (C) a first mortgage given to secure the unpaid purchase price of a fee interest in, or long-term leasehold interest in, real estate consisting of a one-family unit in a multifamily project, including a project in which the dwelling units are attached, or are manufactured housing units, semi-detached, or detached, and an undivided interest in the common areas and facilities which serve the project; and the term “first mortgage” means such classes of first liens as are commonly given to secure advances on, or the unpaid purchase price of, real estate, under the laws of the State, in which the real estate is located, together with the credit instruments, if any, secured thereby.

((b)) The term “mortgagee” includes the original lender under a mortgage, and his successors and assigns approved by the Secretary; and the term “mortgagor” includes the original borrower under a mortgage and his successors and assigns.

((c)) The term “maturity date” means the date on which the mortgage indebtedness would be extinguished if paid in accordance with periodic payments provided for in the mortgage.

((d)) The term “State” includes the several States, and Puerto Rico, the District of Columbia, Guam, the Commonwealth of the Northern Mariana Islands, American Samoa, and the Virgin Islands.

((e)) The term “family member” means, with respect to a mortgagor under such section, a child, parent, or grandparent of the mortgagor (or the mortgagor’s spouse). In determining whether any of the relationships referred to in the preceding sentence exist, a legally adopted son or daughter of an individual (and a child who is a member of an individual’s household, if placed with such individual by an authorized placement agency for legal adoption by such individual), and a foster child of an individual, shall be treated as a child of such individual by blood.

((f)) The term “child” means, with respect to a mortgagor under such section, a son, stepson, daughter, or stepdaughter of such mortgagor.

((g)) The term “real estate” means land and all natural resources and structures permanently affixed to the land, including residential buildings and stationary manufactured housing. The Secretary may not require, for treatment of any land or other property as real estate for purposes of this subchapter, that such land or property be treated as real estate for purposes of State taxation.